Super-dosing effects of phytase in poultry and other monogastrics

Heat Stress in Japanese Quails (Coturnix japonica): Benefits of Phytase Supplementation

In tropical and subtropical climate regions, heat stress is one of the main causes of production losses in laying quails, aggravated by the antinutritional effects of the phytate in diet ingredients, which negatively affect the bioavailability of minerals, especially calcium and phosphorus. This situation results in a reduction in production and the quality of eggs from commercial laying quails. Several nutritional strategies are utilized to reduce the adverse effects of high temperatures and antinutritional factors such as phytate. Among these strategies, the use of exogenous enzymes, such as phytase, stands out as a viable alternative. Phytase breaks down phytate molecules, optimizing the absorption of essential minerals and improving productive performance and egg quality under unfavorable conditions. Specifically, it is recommended to use 1500 FTU of phytase, as it not only reduces the effects of thermal stress but also enhances eggshell thickness and calcium absorption. In this context, this bibliographic review sought to produce a document demonstrating the beneficial effects of the phytase enzyme on the hydrolysis of the phytate molecule, the availability of calcium for Japanese quails (Coturnix japonica), and its implications in thermal stress due to heat.

Unlocking Phytate with Phytase: A Meta-Analytic View of Meat-Type Chicken Muscle Growth and Bone Mineralization Potential

The inclusion of exogenous phytase in P- and Ca-deficient diets of broilers to address the growing concern about excessive P excretion into the environment over the years has been remarkably documented. However, responses among these studies have been inconsistent because of the several factors affecting P utilization. For this reason, a systematic review with a meta-analysis of results from forty-one studies published from 2000 to February 2024 was evaluated to achieve the following: (1) quantitatively summarize the size of phytase effect on growth performance, bone strength and mineralization in broilers fed diets deficient in P and Ca and (2) estimate and explore the heterogeneity in the effect size of outcomes using subgroup and meta-regression analyses. The quality of the included studies was assessed using the Cochrane Collaboration's SYRCLE risk of bias checklists for animal studies. Applying the random effects models, Hedges' g effect size of supplemented phytase was calculated using the R software (version 4.3.3, Angel Food Cake) to determine the standardized mean difference (SMD) at a 95% confidence interval. Subgroup analysis and meta-regression were used to further explore the effect size heterogeneity (PSMD ≤ 0.05, I2 > 50%, n ≥ 10). The meta-analysis showed that supplemental phytase increases ADFI and BWG and improves FCR at each time point of growth (p < 0.0001). Additionally, phytase supplementation consistently increased tibia ash, P and Ca, and bone strength (p < 0.0001) of broilers fed P- and Ca-deficient diets. The results of the subgroup and meta-regression analyses showed that the age and strain of broiler, dietary P source, and the duration of phytase exposure significantly influence the effect size of phytase on growth and bone parameters. In conclusion, phytase can attenuate the effect of reducing dietary-available phosphorus and calcium and improve ADFI, BWG, and FCR, especially when added to starter diets. It further enhances bone ash, bone mineralization, and the bone-breaking strength of broilers, even though the effects of bone ash and strength can be maximized in the starter phase of growth. However, the effect sizes of phytase were related to the age and strain of the broiler, dietary P source, and the duration of phytase exposure rather than the dosage.

Effect of day-old chick weight on the response of broilers to high doses of exogenous phytase

A total of 360 Ross 708 male broiler chicks were used in an 8 treatment and 9 replicate cage study to explore the influence of day-old chick weight on the efficacy of exogenous phytase. Treatments were arranged as a 2 × 4 factorial with the factors being diet (a positive (PC) and negative control (NC) varying in nutrient density fed without or with 2 concentrations of exogenous phytase) and chick weight (light; <38.5 g or heavy; >42 g). Chicks were sourced from the same breeder flock, with light and heavy chicks being selected from the naturally occurring heterogeneity in the population. The diets were corn-soybean meal based and the PC was formulated to meet the nutrient requirements of male broiler chicks. The NC was formulated to contain 120 kcal/kg, 0.5, 0.18, and 0.18% less apparent metabolizable energy (AME), crude protein (CP), calcium (Ca), and phosphorus (P), respectively, than the PC. Amino acid (AA) density in the NC was also reduced in line with the reduction in CP and the manufacturers' recommendations for the effect of phytase on amino acid digestibility. Phytase at either 1,000 FYT/kg or 3,000 FYT/kg was added only to the NC to create a total of 4 diets. Water and mash feed were available ad libitum and were offered to 8 replicate cages, each containing 5 chicks. The experiment was conducted over a period of 3 wk and diets were offered in 2 phases (starter from d 1 to 10 and grower from d 11 to 21). Growth performance was monitored at the end of each diet phase and on d 21 ileal digesta were collected for estimation of apparent digestibility of energy (DE), nitrogen (N), Ca, P, dry matter (DM), and AA. There were no statistically significant interactions between diet and day-old chick weight for any of the measured parameters. Light chicks had significantly lower weight gain (approx. 5%) at both d 10 and d 21 compared with heavy chicks. This effect was principally associated with reduced feed intake and there was no significant effect of chick weight on feed conversion ratio (FCR). Chick weight had no effect on ileal nutrient digestibility. The reduction in nutrient density from the PC to the NC generated a significant reduction in weight gain (around 12%) and a significant increase in FCR (1.68 vs. 1.83). This effect was associated with a significant reduction in ileal DE (approximately 150 kcal/kg) and in the digestibility of several AA. Exogenous phytase significantly increased weight gain, reduced FCR and generated a significant increase in the ileal digestibility of energy, N, P, and several AA. Although chick weight and diet did not interact statistically, heavy chicks benefited more than light chicks from high doses of exogenous phytase across almost all measured end points which was confirmed by regression analysis. In conclusion, light chicks have inferior performance outcomes than heavy chicks principally because of reduced feed intake, but putatively not in digestive capacity per se. Exogenous phytase is effective in improving performance and nutrient digestibility in nutrient deficient diets. The effect of chick weight per se, and also breeder flock age, on the utility of supra-nutritional inclusion concentrations of exogenous phytase warrants further study.

A study of solely used phytase or in combination with multi-carbohydrase on growth performance along with tibia mineralization, and carcass traits in broilers fed nutrient-deficient diets

The objective of this study aimed to investigate the effectiveness of phytase alone and in combination with multi-carbohydrase in available phosphorus (AP) and energy-deficient diets on growth performance, nutrient digestibility, tibia traits, and carcass quality of broilers. A total of 288 1-d-old Ross 308 broiler chicks were randomly assigned to one of 6 dietary treatments in a completely randomized design, with each treatment having 6 replicates and 8 birds per cage. The treatments were as follows: 1) positive control with adequate nutrition (PC); 2) 0.20% AP-deficient diet without phytase (NC-1); 3) 0.25% AP-deficient diet without phytase (NC-2); 4) NC-1 diet plus 500 FTU/kg phytase (NCP-1); 5) NC-2 diet plus 750 FTU/kg phytase (NCP-2); and 6) NC-2 with 100 kcal/kg ME deficient diet plus 1,000 FTU/kg phytase and multi-carbohydrase: 2,200 U/kg galactomannanase, 30,000 U/kg xylanase, 22,000 U/kg β-glucanase, and 700 U/kg α-galactosidase (NCPM). Broilers in the PC group and those fed enzyme-supplemented diets exhibited greater (P < 0.05) growth performance in terms of body weight, average daily gain, and feed conversion ratio, along with enhanced tibia mineralization through the ash, calcium (Ca), phosphorus (P) composition, and tibia breaking strength compared to NC diets throughout the study. Among the treatments, broilers assigned to the NCPM group showed greater (P < 0.05) levels of energy and P digestibility on days 21 and 35. Concerning carcass characteristics, the leg meat yield was greater (P < 0.05) in broilers fed the NCP-2 diet compared to all other treatments on days 21 and 35. Supplementation of phytase at doses of 500 FTU/kg and 750 FTU/kg effectively recovers AP deficiencies of 0.20% and 0.25%, respectively, in broiler diets without compromising the growth performance of broilers. Additionally, combining multi-carbohydrase and phytase led to AP and energy loss recovery, which improved tibia mineralization and nutrient digestibility through their synergistic interaction.

Production of fungal phytases in solid state fermentation and potential biotechnological applications

Phytases are important enzymes used for eliminating the anti-nutritional properties of phytic acid in food and feed ingredients. Phytic acid is major form of organic phosphorus stored during seed setting. Monogastric animals cannot utilize this phytate-phosphorus due to lack of necessary enzymes. Therefore, phytic acid excretion is responsible for mineral deficiency and phosphorus pollution. Phytases have been reported from diverse microorganisms, however, fungal phytases are preferred due to their unique properties. Aspergillus species are the predominant producers of phytases and have been explored widely as compared to other fungi. Solid-state fermentation has been studied as an economical process for the production of phytases to utilize various agro-industrial residues. Mixed substrate fermentation has also been reported for the production of phytases. Physical and chemical parameters including pH, temperature, and concentrations of media components have significantly affected the production of phytases in solid state fermentation. Fungi produced high levels of phytases in solid state fermentation utilizing economical substrates. Optimization of culture conditions using different approaches has significantly improved the production of phytases. Fungal phytases are histidine acid phosphatases exhibiting broad substrate specificity, are relatively thermostable and protease-resistant. These phytases have been found effective in dephytinization of food and feed samples with concomitant liberation of minerals, sugars and soluble proteins. Additionally, they have improved the growth of plants by increasing the availability of phosphorus and other minerals. Furthermore, phytases from fungi have played an important roles in bread making, semi-synthesis of peroxidase, biofuel production, production of myo-inositol phosphates and management of environmental pollution. This review article describes the production of fungal phytases in solid state fermentation and their biotechnological applications.

A novel consensus bacterial 6-phytase variant improves the responses of laying hens fed an inorganic phosphorus-free diet with reduced energy and nutrients from 23 to 72 wk of age

The objective of this study was to evaluate the effect of a novel consensus bacterial 6-phytase variant (PhyG) on egg productivity, eggshell quality, and body composition of laying hens fed inorganic phosphate-free diets with reduced energy and nutrients from 23 to 72 wk of age. Five treatments were randomly assigned, performing 28 replicates per treatment with 4 hens each, totaling 560 Hy-Line W80 birds. A positive control (PC) feed was formulated to contain adequate levels of energy and nutrients. A negative control (NC) feed was formulated without added inorganic phosphate (0.12% nonphytic phosphorus [nPP]) and reduced in Ca, Na, dig AA, and metabolizable energy in comparison with PC feed. Phytase was supplemented in the NC feed at 0, 300, 600, and 900 FTU/kg of feed. The responses evaluated were performance, egg quality, economic analysis, body composition, and tibia composition. Data were analyzed by a 2-factor (diet and age) repeated measure analysis. Overall, the feed intake, hen-day egg production, egg mass, and egg revenue were reduced by the complete removal of dicalcium phosphate (DCP) (P < 0.05). Supplement phytase in the NC diet elicits a positive response on each one of those variables. Laying hens consuming the NC feed with 900 FTU/kg of phytase produced more eggs per hen-housed compared with the phytase dosages of 300 and 600 FTU/kg. Body composition was not affected by dietary nPP, Ca, Na, dig AA, and energy reductions (P > 0.05). At 72-wk-old, tibia ash was reduced in hens consuming the NC diet vs. PC (P < 0.05) and no difference was observed between hens supplemented with phytase and the PC feed. Margin over feeding cost increased in a dose-dependent manner with phytase supplementation. Supplementation with 900 FTU/kg of phytase is recommended to improve the number of eggs produced per hen-housed and the number of marketable eggs produced through 23 to 72 wk of age, under this dietary setting.

Calcium Nutrition of Broilers: Current Perspectives and Challenges

Calcium (Ca) plays an essential role in poultry nutrition as 99% of Ca is located in birds' skeletal system. However, oversupply of Ca rather than deficiency of Ca is the current concern in commercial broiler diets. Calcium is an inexpensive dietary nutrient due to the cheap and abundant availability of limestone, the major Ca source; therefore, little attention was given to the oversupply of Ca in the past. The recent shift in the use of digestible P in broiler feed formulations has necessitated a closer look at digestible Ca, as Ca and P are interrelated in their absorption and postabsorptive utilisation. In this context, data on ileal digestibility of Ca and P in ingredients has been determined. Preliminary data on the digestible Ca and digestible P requirements for the different growth stages of broilers have also recently become available. The present review focusses on these recent advances in Ca nutrition. In addition, aspects of homeostatic control mechanisms, different Ca sources and factors influencing Ca digestibility in poultry are covered.

Evaluation of phytase dose effect on performance, bone mineralization, and prececal phosphorus digestibility in broilers fed diets with varying metabolizable energy, digestible amino acids, and available phosphorus concentration

The nutritional composition of diets and the provision of exogenous phytases play important roles in animal performance. Therefore, we evaluated the individual and combined impact of metabolizable energy (ME), digestible lysine (dLys), available phosphorus (avP) and calcium (Ca), and phytase dose (1,000 or 2,000 FTU/kg) on the growth performance, feed efficiency, phosphorus digestibility, and bone ash content of broiler chickens from 10 to 42 d of age. Experimental diets were formulated in a Box-Behnken design to contain various levels of ME (11.9, 12.2, 12.54, or 13.1 MJ/kg), dLys (0.91, 0.93, 0.96, or 1.00%) and avP/Ca (0.12/0.47, 0.21/0.58, or 0.33/0.68%). The effect of phytase was expressed in terms of the extra nutrients released. The diets were formulated to have consistent phytate substrate contents (0.28% in average). Body weight gain (BWG) and feed conversion ratio (FCR) were described via polynomial equations (R² = 0.88 and 0.52, respectively), with interconnections between variables (ME, dLys, and avP/Ca). No interaction was observed among variables (P > 0.05). Metabolizable energy was the most important factor affecting BWG and FCR (linearly; P < 0.001). Reducing ME content from 13.1 to 11.9 MJ/kg in control diet resulted in a 6.8% decrease in BWG and a 3.1% increase in FCR (P < 0.001). The dLys contents also affected performance linearly (P < 0.001), but to a lesser degree; BWG decreased by 160 g when the dLys was reduced by 0.09% units, while the same reduction in dLys increased the FCR by 0.108 points. The inclusion of phytase alleviated the negative effects on feed intake (FI), BWG, and FCR. Phytase improved phosphorus digestibility and bone ash content according to a quadratic relationship. When phytase was added, ME negatively affected FI (r = -0.82, P < 0.001), whereas the dLys content was correlated with FCR (r = -0.80, P < 0.001). Supplementing phytase allowed the reduction of ME, dLys, and avP-Ca in the diet without affecting performance. The addition of phytase increased of ME, dLys, and avP by 0.20 MJ/kg, 0.04 and 0.18% units for 1,000 FTU/kg and 0.4 MJ/kg, 0.06 and 0.20% units for 2,000 FTU/kg.

The Contribution of Phytate-Degrading Enzymes to Chicken-Meat Production

The contribution that exogenous phytases have made towards sustainable chicken-meat production over the past two decades has been unequivocally immense. Initially, their acceptance by the global industry was negligible, but today, exogenous phytases are routine additions to broiler diets, very often at elevated inclusion levels. The genesis of this remarkable development is based on the capacity of phytases to enhance phosphorus (P) utilization, thereby reducing P excretion. This was amplified by an expanding appreciation of the powerful anti-nutritive properties of the substrate, phytate (myo-inositol hexaphosphate; IP₆), which is invariably present in all plant-sourced feedstuffs and practical broiler diets. The surprisingly broad spectra of anti-nutritive properties harbored by dietary phytate are counteracted by exogenous phytases via the hydrolysis of phytate and the positive consequences of phytate degradation. Phytases enhance the utilization of minerals, including phosphorus, sodium, and calcium, the protein digestion, and the intestinal uptakes of amino acids and glucose to varying extents. The liberation of phytate-bound phosphorus (P) by phytase is fundamental; however, the impacts of phytase on protein digestion, the intestinal uptakes of amino acids, and the apparent amino acid digestibility coefficients are intriguing and important. Numerous factors are involved, but it appears that phytases have positive impacts on the initiation of protein digestion by pepsin. This extends to promoting the intestinal uptakes of amino acids stemming from the enhanced uptakes of monomeric amino acids via Na⁺-dependent transporters and, arguably more importantly, from the enhanced uptakes of oligopeptides via PepT-1, which is functionally dependent on the Na⁺/H⁺ exchanger, NHE. Our comprehension of the phytate-phytase axis in poultry nutrition has expanded over the past 30 years; this has promoted the extraordinary surge in acceptance of exogenous phytases, coupled with the development of more efficacious preparations in combination with the deflating inclusion costs for exogenous phytases. The purpose of this paper is to review the progress that has been made with phytate-degrading enzymes since their introduction in 1991 and the underlying mechanisms driving their positive contribution to chicken-meat production now and into the future.

Nutritional and Functional Roles of Phytase and Xylanase Enhancing the Intestinal Health and Growth of Nursery Pigs and Broiler Chickens

This review paper discussed the nutritional and functional roles of phytase and xylanase enhancing the intestinal and growth of nursery pigs and broiler chickens. There are different feed enzymes that are currently supplemented to feeds for nursery pigs and broiler chickens. Phytase and xylanase have been extensively studied showing consistent results especially related to enhancement of nutrient digestibility and growth performance of nursery pigs and broiler chickens. Findings from recent studies raise the hypothesis that phytase and xylanase could play functional roles beyond increasing nutrient digestibility, but also enhancing the intestinal health and positively modulating the intestinal microbiota of nursery pigs and broiler chickens. In conclusion, the supplementation of phytase and xylanase for nursery pigs and broiler chickens reaffirmed the benefits related to enhancement of nutrient digestibility and growth performance, whilst also playing functional roles benefiting the intestinal microbiota and reducing the intestinal oxidative damages. As a result, it could contribute to a reduction in the feed costs by allowing the use of a wider range of feedstuffs without compromising the optimal performance of the animals, as well as the environmental concerns associated with a poor hydrolysis of antinutritional factors present in the diets for swine and poultry.

Determination of the standardized ileal digestible calcium requirement of male Arbor Acres Plus broilers from day 25 to 42 post-hatch

An experiment was conducted to determine the standardized ileal digestible (SID) Ca requirement of Arbor Acres Plus male broilers from d 25 to 42 post-hatch. Broilers were obtained at hatch, placed in floor pens, and fed a nutrient adequate diet until d 24 post-hatch. On d 25, twelve hundred birds were weighed and allocated to one of 4 treatments. There were 25 birds per pen and 12 pens per diet. The diets were formulated to contain 0.46, 0.35, 0.24, or 0.13% SID Ca. Available P (avP) was 0.39% in all diets, including 0.16% avP expected from 2,500 FYT/kg of phytase. The SID Ca requirement was estimated using nonlinear models, including quadratic, straight broken-line, and quadratic broken-line. There was no effect of SID Ca on feed intake, body weight gain, feed conversion ratio, or livability. Tibia ash percent was greatest in birds fed 0.35% SID Ca and lowest in birds fed 0.13% SID Ca (quadratic, P = 0.063). Apparent ileal digestibility (AID) of Ca was highest in birds fed the diets containing 0.13% SID Ca and decreased (quadratic, P = 0.014) as dietary SID Ca increased to 0.46%. Apparent digested Ca was highest in birds fed 0.35% SID Ca and lowest in birds fed 0.13% SID Ca (quadratic, P = 0.005). Decreasing the concentration of SID Ca in the diet from 0.46 to 0.13% (P < 0.0001) increased the AID of P and apparent digested P. Litter N or P were lowest in birds fed 0.35% SID Ca and increased (quadratic, P ≤ 0.05) as dietary SID Ca decreased to 0.13%. Non-linear equations, developed using tibia ash percent, digested Ca, or litter P, estimate the SID Ca requirement of Arbor Acres Plus broilers from d 25 to 42 was 0.37, 0.35, or 0.35%, respectively. This corresponds to an SID Ca to available P ratio of 0.95 to 0.90.

Evaluation of High Doses of Phytase in a Low-Phosphorus Diet in Comparison to a Phytate-Free Diet on Performance, Apparent Ileal Digestibility of Nutrients, Bone Mineralization, Intestinal Morphology, and Immune Traits in 21-Day-Old Broiler Chickens

The supplementation of feed with phytases enables broilers to utilize more efficiently phosphorus (P) from phytic acid (IP6), the main storage form of P in plants. The current study evaluated the addition of 500, 1000, and 3000 FTU of phytase per kg to a phytate-containing diet with low P level (LP) fed to broilers from 1 to 21 days of age and compared it to a hypoallergenic phytate-free diet (HPF). There was a linear improvement in performance parameters with increasing levels of phytase in the LP diet (p < 0.001). Apparent ileal digestibility of crude protein, P, and some amino acids, increased with phytase. Crude ash, P, and the calcium content of tibia bones linearly increased with increasing levels of phytase (p < 0.001). Crypt depth (related to body weight) in the jejunum epithelium linearly decreased with phytase addition (p < 0.001). Cecal crypt depth decreased with phytase supplementation (p = 0.002). Cecum tissue showed lower counts of CD3-positive intraepithelial lymphocytes in broilers receiving the phytase in comparison to LP (p < 0.001), achieving similar counts to HPF-fed broilers. Although results from the current study seem to point out some mechanisms related to the immune response and mucosal morphology contributing to those overall beneficial effects, no clear differences between different phytase doses could be demonstrated in these specific parameters.

The Growth Performance, Nutrient Digestibility, Gut Bacteria and Bone Strength of Broilers Offered Alternative, Sustainable Diets Varying in Nutrient Specification and Phytase Dose

This study assessed the use of locally sourced sustainable feed ingredients, rapeseed meal (RSM) and maize dried distiller grains with solubles (DDGS) in diets over traditional ingredients on the growth performance, bone strength and nutrient digestibility of broilers. This work also investigated the effects of supplementing exogenous phytase in two doses (500 vs. 1500 FTU/kg). Using male Ross 308 chicks (n = 320) assigned to receive one of four experimental diets: (1) Positive control diet 1 (PC1), a wheat, soya-based diet + 500 FTU/kg phytase. (2) Positive control diet 2, RSM/DDGS diet + 500 FTU/kg phytase (PC2). (3) Negative control (NC) reduced nutrient RSM/DDGS diet, no phytase. (4) The NC diet plus 1500 FTU/kg phytase (NC+). PC1 birds displayed higher feed intake and body weight gain consistently throughout the trial (p < 0.001) as well as increased body weight by 28 d and 42 d (p < 0.001). Whole-body dual emission X-ray absorptiometry (DXA) analysis revealed PC1 birds also had higher bone mineral density (BMD), bone mineral content (BMC), total bone mass, total lean mass and total fat mass than birds offered other treatments (p < 0.01). Diet had no significant effect on bone strength. Phytase superdosing improved the digestibility of dry matter (DM), neutral detergent fibre (NDF), gross energy (GE), calcium (Ca), potassium (K) and magnesium (Mg) compared to birds in other treatment groups. The phytase superdose also improved performance in comparison to birds offered the NC diet. Phytase superdosing increased the IP6 and IP5 degradation and increased the ileal inositol concentration of the birds. N excretion was lower for birds offered the traditional wheat−soya diet and highest for those offered the high-specification RSM/DDGS diet with a commercial dose of phytase. The addition of a phytase superdose to the negative control diet (NC+) reduced P excretion of birds by 15% compared to birds offered NC.

The role of feed enzymes in maintaining poultry intestinal health

Gut health or intestinal health is frequently discussed without any clear definition as to its meaning. It is suggested that this should be defined as intestinal integrity and functionality as both are a pre-requisite for the health of the intestine itself and the host. The health of the intestine is dependent upon a successful evolution of the absorptive capacity of the intestine, which in turn is influenced by the co-evolution of the intestinal immune systems and the microbiota. Nutrient supply plays a significant role in this process and from the perspective of the microbiota this changes with age as the intestines and upper gastrointestinal tract (GIT) microbiota become more effective in nutrient removal. Feed enzymes play a significant role in this process. Phytases can improve digestion of minerals, amino acids and energy and as a result reduce the availability of nutrients in the lower intestines for the microbiota. Protease can have a similar effect with amino acid supply. Non-starch polysaccharidases (NSPases) have a unique role in that they not only improve diet digestibility from the hosts perspective, thus limiting nutrient supply to the microbiota, but they also release soluble fragments of fibre from the insoluble matrix and/or depolymerize high molecular weight viscous fibre fractions in to smaller, more fermentable carbohydrate fractions. This results in a more favourable balance between fermentable carbohydrate to protein supply, a ratio which is deemed critical to maintaining good intestinal health. The dynamic nature of this complex evolution needs greater consideration if antibiotic free production is to succeed. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of the responses of broiler chickens to varying concentrations of phytate phosphorus and phytase. Ⅱ. Grower phase (day 12-23 post hatching)

A randomized complete block design study used 768 male broiler chickens to investigate the effects of phytate P (PP) and a novel consensus bacterial phytase variant (PhyG) concentration on growth performance, bone mineralization, apparent ileal digestibility (AID), and total tract retention (TTR) of nutrients in broiler chickens. Treatments were arranged in a 1 + 3 × 5 factorial with a nutrient-adequate positive control diet (PC) with 2.8 g PP/kg, 3 nutrient-reduced negative control diets (NC: PC minus 88 kcal/kg ME, 0.8 g/kg dig. Lys, 2.0 g/kg available P, 2.0 g/kg Ca and 0.5 g/kg Na) with varying PP (g/kg) levels, mainly from rice bran, at 2.3 (NC1), 2.8 (NC2), or 3.3 (NC3) and 5 PhyG doses at 0, 500, 1,000, 2,000, or 4,000 FTU/kg. All treatments had 6 replicate cages with 8 birds/cage. A commercial starter diet was fed from d 0 to 12 and the experimental diets from d 12 to 23 post hatching. Birds fed the NC2 diet without phytase had lower (P < 0.01) BW, BW gain, and feed intake (FI) as compared with birds fed the PC with the same PP level. With increasing phytate, there was a decrease (P < 0.05) in BW, BW gain, and FI. Phytase increased (P < 0.01) BW and feed efficiency of broiler chickens. An interaction (P < 0.05) between PP and phytase concentrations was observed on the AID of Met, Cys, and Thr. Linear decrease (P < 0.01) in the AID and TTR of P and Ca with increasing PP concentrations were observed. Phytase supplementation increased (P ≤ 0.05) the AID of P, Ca, and all AA. The TTR of P, Ca, and Zn was linearly increased (P < 0.01) by 112, 123, and 46%, respectively, when birds fed NC diets with 0 and 4,000 FTU/kg were compared. In conclusion, phytate reduced the growth performance and nutrient utilization of broiler chickens from d 12 to 23 post hatching while phytase ameliorated these negative effects.

Dietary Phosphorus and Calcium Utilization in Growing Pigs: Requirements and Improvements

The sustainability of animal production relies on the judicious use of phosphorus (P). Phosphate, the mined source of agricultural phosphorus supplements, is a non-renewable resource, but phosphorus is essential for animal growth, health, and well-being. P must be provided by efficient and sustainable means that minimize the phosphorus footprint of livestock production by developing precise assessment of the bioavailability of dietary P using robust models. About 60% of the phosphorus in an animal's body occurs in bone at a fixed ratio with calcium (Ca) and the rest is found in muscle. The P and Ca requirements must be estimated together; they cannot be dissociated. While precise assessment of P and Ca requirements is important for animal well-being, it can also help to mitigate the environmental effects of pig farming. These strategies refer to multicriteria approaches of modeling, efficient use of the new generations of phytase, depletion and repletion strategies to prime the animal to be more efficient, and finally combining these strategies into a precision feeding model that provides daily tailored diets for individuals. The industry will need to use strategies such as these to ensure a sustainable plant-animal-soil system and an efficient P cycle.

Supplemental Effects of Phytase on Modulation of Mucosa-Associated Microbiota in the Jejunum and the Impacts on Nutrient Digestibility, Intestinal Morphology, and Bone Parameters in Broiler Chickens

This study aimed to determine supplemental effects of phytase on modulation of the mucosa-associated microbiota in the jejunum, intestinal morphology, nutrient digestibility, bone parameters, and growth performance of broiler chickens. Three hundred and sixty newly hatched broiler chickens (Ross 308) (44 ± 2 g BW) were randomly allotted in 6 treatments with 10 birds per cage based on a completely randomized design and fed for 27 d. The treatments consisted of one negative control (NC), diet formulated meeting the requirements suggested by Ross recommendations (2019), and without phytase supplementation. The other treatments consisted of a positive control diet (PC) formulated with 0.15% deficient Ca and P and split into 5 treatments with different phytase inclusion levels (0, 500, 1000, 2000, 4000 FTU/kg feed). Titanium dioxide (0.4%) was added to feeds as an indigestible marker to measure apparent ileal digestibility (AID) of nutrients. On d 27, 3 birds were randomly selected from each cage and euthanized to collect samples for analyzing the mucosa-associated microbiota in the jejunum, oxidative stress status, AID, and bone parameters. Data were analyzed using the proc Mixed of SAS 9.4. Phytase supplementation tended to have a quadratic effect (p = 0.078) on the overall ADG (maximum: 41 g/d at 2833 FTU/kg of feed). Supplementation of phytase at 2,000 FTU/kg increased (p < 0.05) the relative abundance of Lactobacillus and reduced (p < 0.05) Pelomonas. Moreover, it tended to reduce Helicobacter (p = 0.085), Pseudomonas (p = 0.090) Sphingomonas (p = 0.071). Phytase supplementation increased (p < 0.05) the villus height and the AID of CP; and tended to increase (p = 0.086) the AID of P. Phytase supplementation increased (p < 0.05) breaking strength and P content in the tibia. In conclusion, phytase supplementation showed potential benefits on the modulation of the mucosa-associated microbiota in the jejunum by tending to reduce harmful bacteria (Pelomonas, Helicobacter, and Pseudomonas) and increase beneficial bacteria (Lactobacillus). In addition, it showed positive effects increasing apparent ileal digestibility of CP and P, enhancing intestinal morphology (villus height), and improving the bone parameters (bone breaking strength, ash, and P content). Phytase supplementation at a range of 38 to 59 FTU/d or 600 to 950 FTU/kg of feed provided the most benefits related to nutrient digestibility.

Effects of adding high-dosing Aspergillus oryzae phytase to corn-wheat-soybean meal-based basal diet on growth performance, nutrient digestibility, faecal gas emission, carcass traits and meat quality in growing-finishing pigs

This study tests the effects of supplementation of high-dosing Aspergillus oryzae phytase into the corn-wheat-soybean meal (SBM)-based basal diet on growth performance, nutrient digestibility, faecal gas emission, carcass traits and meat quality in growing-finishing pigs (29.73-110.86 kg live weight; 70-day-old to 166-day-old). A total of 56 crossbred pigs [(Landrace × Yorkshire) × Duroc] were divided into two dietary groups for a 96-day experiment (growing period, days 0-42; finishing period, days 43-96) with a completely randomized block design. There were seven replicate pens in each dietary group, and each pen has four pigs (two barrows and two gilts). The dietary treatments consisted of a corn-wheat-SBM-based nutrient sufficient basal diet or the basal diet supplemented with 1500 FTU/kg A. oryzae phytase. One phytase unit (FTU) was defined as the amount of enzyme that catalyses the release of one micromole phosphate from phytate/min at 37°C and pH 5.5. Higher average daily gain and lower feed conversion ratio were observed in growing-finishing pigs consuming a high-dosing A. oryzae phytase supplementing diet during days 0-42 and 0-96. Supplementing high-dosing A. oryzae phytase to the diet of growing-finishing pigs increased apparent total tract digestibility of phosphorus on days 42 and 96. Moreover, growing-finishing pigs fed the diet supplemented with high-dosing A. oryzae phytase had higher carcass back-fat thickness than those fed the control diet. However, the faecal gas emission and meat quality were not affected by high-dosing A. oryzae phytase supplementation. In conclusion, dietary supplementation of high-dosing A. oryzae phytase (1500 FTU/kg) had beneficial effects on the growth performance, apparent phosphorus digestibility and carcass back-fat thickness in growing-finishing pigs.

Effect of Dietary Mineral Content and Phytase Dose on Nutrient Utilization, Performance, Egg Traits and Bone Mineralization in Laying Hens from 22 to 31 Weeks of Age

Simple Summary

The aim of this work was to elucidate how the dietary inclusion of phytase, at a normal dose and overdosed, could affect the utilization of nutrients and performance in young laying hens. When a diet deficient in Ca and P was applied, the dietary inclusion of phytase at low doses (500 FTU/kg) led to an improvement in the digestive efficiency of P in the first weeks after introduction. However, when these deficient diets were maintained in the long term, laying hens improved their digestive utilization of both Ca and P, a higher dose of phytase (1000 FTU/kg) being required to achieve greater P availability. This overdosage also provided additional extraphosphoric advantages, slightly improving access to other nutrients and the feed conversion rate of the hens.

Abstract

A total of 192 laying hens were used to evaluate the effect of dietary mineral content and phytase dose on nutrient utilization, egg production and quality and bone mineralization of young laying hens. Four dietary treatments were studied: PC, positive control with no added phytase, 4.07% Ca and 0.61% P; NC, negative control with no added phytase, 2.97% Ca and 0.37% P; and P500 and P1000, where NC diet was supplemented with phytase at 500 and 1000 FTU/kg, respectively. Hens’ performance and egg traits were controlled from 22 to 31 weeks of age. Coefficients of total tract apparent digestibility (CTTAD) of nutrients were determined at 25 and 31 weeks of age. Apparent ileal digestibility (AID) and blood content of Ca and P, as well as bone traits, were determined at 31 weeks of age. Ca and P retention was higher in birds on PC diet at 25 weeks, but not at 31 weeks of age compared to those on NC diet (p < 0.05). P1000 birds had the highest CTTAD values for dry and organic matter at both ages (p < 0.001). CTTAD of Ca was significantly higher in P1000 diet than in NC diet at 31 weeks of age (p < 0.001). Birds fed with P500 diet at 25 weeks of age and P1000 at 31 weeks of age showed higher CTTAD and retention of P, but lower excretion of P than those fed NC diet (p < 0.05). Phytase inclusion linearly increased AID of dry matter and P (p < 0.001). P500 hens fed had the greatest body weight at the end of the trial (p < 0.05) and P1000 birds had the best feed conversion ratio (p < 0.05). Fowl fed a PC diet produced eggs with higher shell thickness and yolk color than those fed on NC diet (p < 0.05). Phytase inclusion linearly increased the yolk color (p < 0.05). Tibia of laying hens fed with PC had significantly higher ash content than those on NC diet (p < 0.05), and birds fed with P1000 presented intermediate values. It can be concluded that it would be advisable to increase the dose of phytase in the feed of laying hens to obtain long-term benefits.

Effects of supplementation of high-dosing Trichoderma reesei phytase in the corn-wheat-soybean meal-based diets on growth performance, nutrient digestibility, carcass traits, faecal gas emission, and meat quality in growing-finishing pigs

We conduct this study to investigate the effects of corn-wheat-soybean meal (SBM)-based diet supplemented with high-dosing Trichoderma reesei phytase on the growth performance, nutrient digestibility, carcass traits, faecal gas emission and meat quality in growing-finishing pigs (29.71-110.58 kg live weight; 70-day-old to 166-day-old). A total of 56 crossbred pigs [(Landrace × Yorkshire) × Duroc] were used in 96-day experiment with a completely randomized block design. The growing period was from day 0 to 42, and the finishing period was from day 43 to 96. Pigs were randomly allocated to one of two treatments with seven replicate pens and four pigs (two barrows and two gilts) per pen and fed corn-wheat-SBM-based nutrient adequate basal diet or the basal diet supplemented with 1500 FTU/kg diet Trichoderma reesei phytase. One phytase unit (FTU) was defined as the amount of enzyme that catalyses the release of one micromole phosphate from phytate per minute at 37°C and pH 5.5. Dietary supplement with Trichoderma reesei phytase had increased body weight on day 96 and average daily gain in days 0-96. Moreover, high apparent total tract digestibility (ATTD) of phosphorus (P) was observed in pigs fed with Trichoderma reesei phytase. However, the carcass traits, faecal gas emission and meat quality of pigs were unaffected by Trichoderma reesei phytase supplementation. In conclusion, supplementation of high-dosing Trichoderma reesei phytase (1500 FTU/kg diet) in the corn-wheat-SBM-based nutrient adequate basal diet increased body weight and the ATTD of P, while no adverse effects were observed on the production characteristics.

High doses of phytase on growth performance, bone mineralization, diet utilization, and plasmatic myo-inositol of turkey poults

An experiment was conducted to evaluate the growth performance, bone mineral composition, diet utilization, and plasmatic concentration of myo-inositol (MYO) in turkeys fed different phytase doses from 1 to 28 d. A total of three hundred and twenty 1-day-old turkeys were distributed in a completely randomized design with 4 treatments and 8 replicates of 10 birds each. Treatments included a basal diet without phytase; reduced diet (reduced -0.15% available P and -0.18% Ca) without phytase; reduced diet + 2,000 units of phytase (FYT)/kg; and reduced diet + 4,000 FYT/kg. From day 26 to 28, partial excreta collection was conducted, and on day 28, 7 birds per replicate were euthanized for collection of ileal content and left tibia bones were removed from 2 of the same euthanized birds. Feed, excreta, and ileal digesta samples were analyzed to determine nutrient digestibility and metabolizability, ileal digestible energy, and AME. Tibia bones were analyzed for ash, Ca, and P content, and calculation of Seedor index. On day 28, blood samples were collected from 2 turkeys per replicate to analyze plasmatic MYO concentration. Feed conversion ratio was not affected, but phytase supplementation resulted in higher feed intake and body weight gain compared to turkeys fed the reduced diet (P < 0.05), and both doses were similar to the basal diet. Increasing the phytase dose had a linear effect (P < 0.05) on ileal digestibility of P and metabolizability of DM, CP, Ca, and Na, and also on AME. P content in the tibia bone increased linearly (P < 0.05) with phytase supplementation, and the same linear increase (P < 0.05) was observed for plasmatic MYO. In conclusion, the supplementation of turkey poult's diets with high levels of phytase up to 4,000 FYT/kg improves diet utilization by increasing P digestibility and dietary metabolizability, leading to higher P content in the bone and enhancing MYO provision and absorption.

True ileal calcium digestibility in soybean meal and canola meal, and true ileal phosphorous digestibility in maize-soybean meal and maize-canola meal diets, without and with microbial phytase, for broiler growers and finishers

1. Published data on the ileal Ca digestibility in soybean meal (SBM) and canola meal (CM), and the effect of microbial phytase on the Ca digestibility of these ingredients are limited. Therefore, two experiments were conducted, with the primary objective of determining the true ileal digestibility of calcium (Ca) in SBM and CM, without and with microbial phytase, during broiler grower (Experiment 1) and finisher (Experiment 2) periods. A secondary objective was to investigate the influence of microbial phytase on the true ileal digestibility of phosphorus (P), apparent digestibility of nitrogen (N) and minerals, and phytate disappearance in maize-SBM and maize-CM diets. Six experimental diets based on SBM and CM, with three phytase doses (0, 500 and 2000 FTU/kg), were fed to broilers from day 18 to 21 (Experiment 1) or 39 to 42 (Experiment 2) post-hatch. A Ca- and P-free diet, with no added phytase, was also developed to determine the endogenous Ca and P losses. Titanium dioxide was incorporated in all diets as an indigestible indicator. Each experimental diet was randomly allocated to six replicate cages (eight birds per cage). Apparent ileal digestibility was calculated using the indicator method and the true ileal digestibility was calculated by correcting for endogenous losses. Apparent total tract retention (ATTR) of Ca and P was also measured.2. Ileal endogenous losses of Ca and P were determined to be 236 and 310 mg/kg of dry matter intake (DMI), respectively, in broiler growers and 29 and 130 mg/kg of DMI, respectively, in broiler finishers. True ileal Ca digestibility coefficients of SBM and CM, without added phytase, were determined to be 0.51 and 0.53, respectively, in broiler growers and 0.33 and 0.22, respectively, in broiler finishers. Increasing phytase doses increased (P < 0.05) the true ileal Ca digestibility of CM in both broiler growers and finishers, but Ca digestibility of SBM increased (P < 0.05) only at the superdose (2000 FTU/kg) in broiler finishers. The ATTR of Ca (P < 0.001) in growers was higher in CM than in SBM and was increased in both ingredients by increasing phytase doses. In finishers, the ATTR of Ca was increased (P < 0.001) by both phytase doses in CM, but only by the superdose in SBM, resulting in an ingredient × phytase interaction (P < 0.001).3. True ileal P digestibility coefficients of maize-SBM and maize-CM diets, without added phytase, were determined to be 0.89 and 0.66, respectively, in broiler growers and 0.82 and 0.57, respectively, in broiler finishers. Supplemental phytase increased (P < 0.05) the true ileal P digestibility of the maize-CM diet in both broiler growers and finishers. However, the P digestibility of the maize-SBM diet was increased (P < 0.05) in broiler finishers only at the superdose (2000 FTU/kg). The ATTR of P was higher (P < 0.001) in the maize-SBM diet during both periods.4. The apparent ileal digestibility of N, Mg, K and Mn was higher (P < 0.001) in the maize-SBM diet for broiler growers and finishers. Phytase addition had no effect (P > 0.05) on the apparent digestibility of N and minerals in growers and finishers.5. Increasing phytase doses increased IP6 disappearance in the maize-CM diet, but not in the maize-SBM diet, resulting in an ingredient × phytase interaction (P < 0.001) for growers and finishers.6. In conclusion, true ileal Ca digestibility coefficients of SBM and CM for broilers were determined in this study. The findings confirmed the influence of broiler age of Ca digestibility. Superdosing of phytase increased the digestibility and ATTR of Ca in CM and SBM by two-fold compared to the normal phytase dose.

Dietary betaine reduces plasma homocysteine concentrations and improves bone strength in laying hens

1. This study tested the hypothesis that the methyl-donor properties of betaine could reduce homocysteine concentrations, which has been recognised in a previous genetics study to be linked to bone quality. This was combined with phytase treatment, as phosphorus is critical for bone mineralisation.2. Using a 2 × 2 factorial arrangement, a total of 1920 Lohmann LSL-lite chickens housed as 24 replicates of 20 chickens were fed one of four diets containing dietary betaine (0 or 1000 mg/kg) and phytase (300 or 1000 FTU/kg) from one day old until end-of-lay. Blood and bone samples were collected at 45 and 70 weeks of age.3. Hens fed betaine had lower plasma homocysteine level (P < 0.05), higher tibia breaking strength (P < 0.05) and higher tibia bone density (P < 0.05).4. Egg production and quality was excellent throughout the study and were not affected by the dietary treatments.5. The addition of dietary betaine was successful at reducing plasma homocysteine concentrations and improving bone strength in laying hens, which could be used as an intervention to alleviate welfare concerns.

Effect of high-phytase supplementation in lactation diets on sow and litter performance

A total of 109 sows (Line 241; DNA, Columbus, NE) were used to evaluate the effect of increasing dietary phytase in lactation diets, already adequate in P, on sow and litter performance. On d 107 of gestation, sows were blocked by body weight and parity and allotted to 1 of 3 dietary treatments of increasing phytase concentration (0, 1,000, or 3,000 FYT/kg; Ronozyme HiPhos GT 2700, DSM Nutritional Products, Inc., Parsippany, NJ). The control diet contained no phytase and was formulated to contain 0.50% standardized total tract digestible phosphorus (STTD P; 0.45% available P) and 0.62% STTD calcium (0.90% total Ca). The phytase diets that contained 1,000 or 3,000 FYT/kg were also formulated to 0.50% STTD P and 0.62% STTD Ca including the release of 0.132% STTD P and 0.096% STTD Ca. Diets were balanced for net energy and fed from d 107 of gestation until weaning (d 18 ± 3). All farrowings were monitored, with farrowing duration starting at the time the first pig was born until the first dispersal of placental tissues with no subsequent pigs born. Litters were cross-fostered within treatment until 48 h postfarrowing to equalize litter size. There were no differences among treatments in sow body weight at d 107 of gestation, 24 h after farrowing, or at weaning. Sow average daily feed intake from farrowing to weaning tended to increase (linear, P = 0.093) as phytase increased. There was no evidence for difference in the number of total born pigs, as well as the percentage of stillborns, mummies, and born alive pigs at the completion of farrowing. Similarly, phytase supplementation did not influence (P > 0.05) wean-to-estrus interval or litter size after cross-fostering among dietary treatments. Although not significant (linear, P = 0.226), farrowing duration decreased as added phytase increased with a decrease of 47 min (12%) for 3,000 FYT compared with the control. There were no differences in pig weight at weaning, but as a result of increased survivability (linear, P = 0.002), litter weaning weight and overall litter weight gain increased (quadratic, P < 0.05) up to 1,000 FYT of added phytase with no further benefit observed in sows fed 3,000 FYT. In conclusion, sow feed intake tended to increase linearly with increasing added phytase. Feeding 1,000 FYT/kg maximized overall litter gain and weaning weight; however, a larger-scale study with more sows is needed to determine the addition of phytase in lactation diets to reduce farrowing duration.

Multienzyme Super-Dosing in Broiler Chicken Diets: The Implications for Gut Morphology, Microbial Profile, Nutrient Digestibility, and Bone Mineralization

Simple Summary

Optimizing the gut microbial community and morphometrical traits has become an increasingly prominent area of research due to recent evidence that suggests gut health and functionality affects the production performance of broilers. Creating a diverse microbial population can increase the nutrient digestibility of feed, as the microbes can break down a large portion of macromolecules and convert them into bioavailable substrates to be utilized by the host. A diverse microbiome can be promoted by a variety of additives, including feed enzymes. This study investigated the impact of the application of super-dosing multienzymes on gut morphology, microbial profile, nutrient digestibility, and bone mineralization in broiler chickens. Results found that super-dosing multienzymes improved nutrient digestibility, maintained a diverse microbial population, and tended to increase the overall villi morphology. Bone mineralization was not affected by increasing multienzyme doses. Additionally, the present study found three bacteria that were unique to multienzyme inclusion at a super-dose level.

Abstract

Optimizing gut health has a large impact on nutrient digestibility and bioavailability, and super-dosing feed enzymes may be one solution to achieve this. A 42-day grow-out trial was conducted using 192 Ross 308 broilers to determine if super-dosing Natuzyme at 0 g/t, 350 g/t, 700 g/t, and 1000 g/t dose rates could improve the gut morphology, alter the cecal microbial profile, enhance bone mineralization, and improve nutrient digestibility of a wheat–corn–soybean diet (six replicates per treatment, eight birds per pen). One bird per pen was slaughtered at day 42 and gut morphology, cecal microbial profile, and nutrient digestibility were studied. The addition of enzymes tended to increase the villus height in the duodenum, villus height, width, and crypt depth in the jejunum, and villus width and the number of goblet cells in the ileum. Microbial profiling revealed diverse communities; however, they did not significantly differ between treatment groups. Yet, 700 g/t Natuzyme promoted microbes belonging to the genus Romboutsia and Ruminococcus gauvreauii, while 1000 g/t Natuzyme promoted Barnesiella species. The nutrient digestibility demonstrated a significant improvement in all enzyme doses compared to the control. In conclusion, based on the outcomes of this study, a dose rate of 700 g/t Natuzyme is recommended to improve gut morphology and nutrient digestibility, and promote unique microbes which aid in feed efficiency.

Ileal Digestibility and Total Tract Retention of Phosphorus in Inorganic Phosphates Fed to Broiler Chickens Using the Direct Method

The objective of this study was to determine and compare the phosphorus (P) utilization of inorganic phosphates fed to broiler chickens using the direct method. On day 15 of age, six hundred forty 15-day-old male Ross 308 broiler chickens (initial body weight = 399 ± 38 g) were assigned to five experimental diets with 16 birds per cage in a randomized complete block design. The experimental diets consisted of four semi-purified diets containing monocalcium phosphate, monodicalcium phosphate, dicalcium phosphate, and tricalcium phosphate as the sole P sources. Additionally, a P-free diet was prepared to measure basal endogenous P loss. Chromic oxide was added to the experimental diets as an indigestible index. Excreta were collected per cage on days 17 to 18 of age, and all birds were asphyxiated with carbon dioxide on day 19 of age for ileal digesta collection. The cage was an experimental unit, and the number of replications per each treatment was eight except for the tricalcium phosphate treatment (n = 4). There was no interaction observed between the P source and the collection site (ileal digestibility vs. total tract retention). Phosphorus utilization differed (p < 0.05) among inorganic phosphates and the ileal digestibility of P was greater (p < 0.05) than the total tract retention. In conclusion, the standardized ileal digestibility of P in inorganic phosphates ranged from 56.7% to 89.8% and ileal digestibility was greater than the total tract retention.

Research Note: The effect of sequential displacement of dietary dextrose with myo-inositol on broiler chicken growth performance, bone characteristics, ileal nutrient digestibility, and total tract nutrient retention

A total of 480 male Cobb 500 broiler chicks were assigned to one of 6 dietary treatments to explore the energy equivalence of myo-inositol compared with dextrose. The 6 dietary treatments included a corn and soy-based control ration formulated with 5% anhydrous dextrose and 5 further diets that were generated by the sequential displacement of increments of 1% dextrose with myo-inositol. Each diet was fed to 8 replicate cages of 10 chicks per cage from day 8 to day 18 after hatch. The BW gain, feed intake, and feed conversion ratio (FCR) were measured, and on day 15 to day 17, excreta were collected to estimate the total tract nutrient retention. Ileal digestibility of nutrients and tibia mineral content was assessed on day 18. The displacement of dextrose with myo-inositol generated a significant linear reduction in the FCR that did not reach a plateau at 5% dietary inclusion of myo-inositol. There was no effect of the displacement of dextrose with myo-inositol on bone mineral concentration. However, supplemental myo-inositol linearly reduced ileal digestibility of DM, calcium, and ileal digestible energy. Myo-inositol addition resulted in a significant linear increase in the total tract retention of CP. It can be concluded that myo-inositol has an energy equivalence equal to approximately 78% of that of dextrose for young broiler chicks but exerts a range of extra caloric effects that improve feed efficiency and may influence nitrogen (N) retention and the uric acid cycle. Future work should focus on the role of phytase and myo-inositol on uric acid, creatine kinase, and other metabolites involved in renal function and biochemical flows of N in urine and feces in nonruminants.

Supplemental phytase derived from E. coli in different concentrations on performance, bone mineralization and cost of broilers diets

The trial was conducted to evaluate the supplementation of E. coli phytase on performance, weight and ash of bones, as well as to determine the bioavailability of P and cost/benefit of its use in diets. A total 1,890 Cobb male day old chicks were assigned to six treatments and seven replicates with 45 birds each, distributed in a completely randomized design. The treatments were: Positive Control; Negative Control (NC1) - reduction of 0.06% avP; Negative Control 2 (NC2) - reduction of 0.12% avP; NC2 + Phytase (120 OTU); NC2 + Phytase (180 OTU); NC2 + Phytase (240 OTU), being 1 OTU equivalent to approximately 2 FTU. With different phytase inclusions, it was possible to verify a gradual increase on body weight gain, feed intake, feed conversion ratio, viability and even the bone characteristics of broilers fed diets containing reduction of P. The closest levels to the highest studied (240 OTU) showed the best results. The replacement of dicalcium phosphate by phytase supplementation is economically viable when the cost per OTU does not exceed US$ 1.4 × 10-5, US$1.2 × 10-5 and US$ 1.0 × 10-5 for the concentrations of 120, 180 and 240 OTU, respectively.

Assessing current phytase release values for calcium, phosphorus, amino acids, and energy in diets for growing-finishing pigs. Transl Anim Sci 2020;4:txaa034. [PMID: 32705032 DOI: 10.1093/tas/txaa034]

Two experiments were conducted to determine the effects of feeding 1,500 phytase units (FYT/kg; Ronozyme HiPhos 2,500; DSM Nutritional Products, Parsippany, NJ) when credited with its corresponding nutrient release values to growing-finishing pigs. The assumed phytase release values were 0.146% standardized total tract digestible (STTD) P, 0.102% STTD Ca, 8.6 kcal/kg of net energy (NE), and 0.0217%, 0.0003%, 0.0086%, 0.0224%, 0.0056%, 0.0122%, and 0.0163% standardized ileal digestible Lys, Met, Met+Cys, Thr, Trp, Ile, and Val, respectively. In Exp. 1, 1,215 pigs (PIC 359 × Camborough, initially 28.0 ± 0.46 kg) were used. Pens were assigned to one of three dietary treatments with 27 pigs per pen and 15 pens per treatment. Experimental diets consisted of a control with no added phytase or diets with 1,500 FYT fed either in the grower period (days 0-57) then switched to the control diet until market or fed throughout the entire study (day 0 to market). Diets containing added phytase were adjusted based on the supplier-provided expected nutrient release values. During the grower period, pigs fed the control diet with no added phytase had increased (P < 0.05) average daily gain (ADG) and gain-to-feed ratio (G:F) compared with pigs fed added phytase. Overall, pigs fed either the control or phytase only in the grower period had increased (P < 0.05) ADG and G:F compared with pigs fed phytase until market. In Exp. 2, 2,268 pigs (PIC 337 × 1050, initially 28.5 ± 1.96 kg) were used. There were six dietary treatments with 27 pigs per pen and 14 pens per treatment. Experimental diets consisted of a control with no added phytase or five diets with 1,500 FYT assuming nutrient release values for Ca and P; Ca, P, and Amino Acid (AA); Ca, P, AA, and half of the suggested NE; Ca, P, AA, and full NE; or no nutrient release. Overall, there was no evidence for difference in ADG or average daily feed intake among treatments; however, pigs fed the diet containing 1,500 FYT assuming that no nutrient release had improved (P < 0.05) G:F compared to pigs fed diets containing 1,500 FYT assuming either Ca and P or Ca, P, AA, and full NE release, with others intermediate. In summary, pigs fed phytase-added diets accounting for full nutrient release values in both experiments had the poorest performance. This suggests that using all of the nutrient release values attributed to this source of phytase was too aggressive and resulted in lower nutrient concentrations than needed to optimize performance.

Does dietary supplementation with phytases affect the thermoregulatory and behavioral responses of pullets in a tropical environment?

Dietary supplementation of two types of phytases (fungal and bacterial) with different dosages (300 and 900 FTUs) was evaluated in the thermoregulatory and behavioral responses of replacement pullets in a tropical environment. 288 Hy-Line White laying birds with a mean weight of 639.60 ± 6.05 g, clinically healthy, and eight weeks old were used in the study. Respiratory rate (RR, breaths. min^-1), Cloacal temperature (CT, °C), Surface temperature with feathers (STWF, °C), and Surface temperature featherless (STF, °C) were measured in the morning and afternoon. Behavioral data were observed through the following activities: sitting, eating, drinking, exploring feathers (EF), non-aggressive pecking (NAP), and object pecking (OP) recorded every 10 min from 6 a.m. to 5 p.m. Environmental variables were measured along with thermoregulatory and behavioral responses. There was an interaction for RR between phytase and period of the day (P < 0.05). The lowest RR (morning) was observed in fungal phytase. STF and STWF were higher (P < 0.05) in the afternoon. Birds supplemented with fungal phytase showed lower STWF (P < 0.05). The variables that contributed to explain physiological and behavioral responses are shown in order of importance for (i) periods of day: morning (sitting, STWF, drinking, eating, and CT) and afternoon (STF, STWF, OP, drinking, eating, RR and sitting); (ii) phytases: fungal (STF, STWF, RR, sitting, eating and drinking); and bacterial (RR, STF, STWF, CT and sitting). Thermoregulatory and behavioral responses were similar between dosages, but different between types of phytases. Birds supplemented with fungal phytase used sensible heat dissipation mechanisms and exhibited thermal comfort behaviors. The 300 and 900 FTUs phytase doses did not influence the thermoregulatory and behavioral responses of birds, while they showed natural heat dissipation and heat stress behaviors in the afternoon. We recommend a dietary supplementation of 300 FTUs fungal phytases.

Standardized total tract digestible phosphorus requirement of 6 to 13 kg pigs fed diets without or with phytase

Dietary phosphorus concentration greatly affects pig's growth performance, environmental impact and diet cost. A total of 1080 pigs (initially 5.9 ± 1.08 kg) from three commercial research rooms were used to determine the effects of increasing standardized total tract digestible (STTD) P concentrations in diets without and with phytase on growth performance and percentage bone ash. Pens (10 pigs/pen, 9 pens/treatment) were balanced for equal weights and randomly allotted to 12 treatments. Treatments were arranged in two dose titrations (without or with 2000 units of phytase) with six levels of STTD P each. The STTD P levels were expressed as a percentage of NRC (2012) requirement estimates (% of NRC; 0.45 and 0.40% for phases 1 and 2, respectively) and were: 80%, 90%, 100%, 110%, 125% and 140% of NRC in diets without phytase and 100%, 110%, 125%, 140%, 155% and 170% of NRC in diets with phytase. Diets were provided in three phases, with experimental diets fed during phases 1 (days 0 to 11) and 2 (days 11 to 25), followed by a common diet from days 25 to 46. On day 25, radius samples from one median-weight gilt per pen were collected for analysis of bone ash. During the treatment period, increasing STTD P from 80% to 140% of NRC in diets without phytase improved average daily gain (ADG; quadratic, P < 0.01), average daily feed intake (ADFI; quadratic, P < 0.05) and gain-feed ratio (G : F; linear, P < 0.01). Estimated STTD P requirement in diets without phytase was 117% and 91% of NRC for maximum ADG according to quadratic polynomial (QP) and broken-line linear (BLL) models, respectively, and was 102%, 119% and >140% of NRC for maximum G : F using BLL, broken-line quadratic and linear models, respectively. When diets contained phytase, increasing STTD P from 100% to 170% of NRC improved ADG (quadratic, P < 0.05) and G : F (linear, P < 0.01). Estimated STTD P requirement in diets containing phytase was 138% for maximum ADG (QP), and 147% (QP) and 116% (BLL) of NRC for maximum G : F. Increasing STTD P increased (linear, P < 0.01) the percentage bone ash regardless of phytase addition. When comparing diets containing the same STTD P levels, phytase increased (P < 0.01) ADG, ADFI and G : F. In summary, estimated STTD P requirements varied depending on the response criteria and statistical models and ranged from 91% to >140% of NRC (0.41% to >0.63% of phase 1 diet and 0.36% to >0.56% of phase 2 diet) in diets without phytase, and from 116% to >170% of NRC (0.52% to >0.77% of phase 1 diet and 0.46% to >0.68% of phase 2 diet) for diets containing phytase. Phytase exerted an extra-phosphoric effect on promoting pig's growth and improved the P dose-responses for ADG and G : F.